Profile: Krueger Sentry Gauge Co., Inc. manufactures liquid level gauges, overfill alert gauges and leak detection gauges. The barrel gauge type B is a reliable, swing arm type barrel monitor used for measuring all types of liquid levels. This liquid level gauge is made specifically for standing and horizontal barrels. We can accomodate 55, 30 and 15 gallon drums and offer multiple materials of construction to accomodate nearly any type of liquid. Overfill alert gauge is a visual gauge designed to visually alert when the tank is near full. Leak detection gauges is a vertical type leak monitor used for detecting leaks in the annular/interstitial space of a double wall above ground containment tank.